EHX - Small Clone - Difference in schematic !?

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Ricotjuh
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Post by Ricotjuh »

Gentlemen, I have the following question.
On the internet I see a difference in the schematics of the small clone.
I am talking about the Tonepad schematic and the original EHX schematic.
With the version of Tonepad, pin 2 of ic1 is connected via a network of 6k8 and a 10nF to 4.5V.
On the original version, this network is not connected to 4.5V but to GND!?!
Which of the two is right ?!

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Ricotjuh
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Post by Ricotjuh »

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Macimalac
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Post by Macimalac »

There is no DC flow at this point, so both should work.
The second one, tied to the half of the power supply (4.5V, the reference voltage of the opamps) theoretically might be better.

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POTL
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Post by POTL »

The capacitor 10n blocks the direct current, so there is no difference.

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Ricotjuh
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Post by Ricotjuh »

Okay clear. But what is the reason that this is linked to DC?

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mictester
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Post by mictester »

It's part of the gain setting for the op-amp. The gain is determined by the feedback resistance divided by the resistance to ground (or half rail - both are at AC ground) plus 1 (not that this will be significant). The capacitor gives frequency dependent gain, as the impedance of the capacitor reduces as the frequency rises - this will give (effectively) treble boost. The output stage has a corresponding treble cut network, to give an overall flat response, but the signal to noise ratio is improved, since most of the noise is at high frequency..... It's a simple and cheap noise reduction circuit.
"Why is it humming?" "Because it doesn't know the words!"

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Ricotjuh
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Post by Ricotjuh »

Thank you for the reply.
Is now clear to me.

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taxfree
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Post by taxfree »

Is there any way to reduce the highs and increase the mids and lows? I built the Small Clone and when I turn the pedal on, I notice that it is thinner than the sound when the pedal is off.

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